1. Field of the Invention
The present invention relates to an ophthalmologic apparatus used in an ophthalmologic doctor's office, or used for a group medical examination or the like.
2. Related Background Art
Up to now, an objective lens commonly used for both an illumination optical system and an image taking optical system is provided in an ophthalmologic apparatus. A black point is provided in the illumination optical system in order that reflection light caused by reflecting illumination light on the objective lens is prevented from appearing on an eye fundus image to form a ghost image, and also from mixing into measurement light to reduce measurement precision.
In particular, in the case of a double scanning type laser scanning ophthalmoscope, the black point for suppressing the formation of the ghost image resulting from the reflection light on an optical member cannot be disposed. Therefore, instead of using a refractive optical member such as a lens, a reflective optical member such as a mirror is used.
Even in an ocular refractive power measuring apparatus such as an autorefractometer, the black point is provided in a projection system in order to prevent measurement index projection light from being reflected on the objective lens. In addition, the objective lens is tilted so as not to affect the measurement precision by the reflection light.
However, in the above-mentioned conventional examples, it is difficult to completely remove ghost light with the black point. In addition, a problem in that the shadow of the black point reflects on the eye fundus image to reduce an image quality is caused.
Further, when the ghost light is removed, it is necessary to provide the objective lens with an antireflection film having a high performance, leading to a problem in that parts become expensive.
In particular, in the case of the double scanning type laser scanning ophthalmoscope, a reflective optical system is complex and hard to adjust. In addition, there is a problem in that a size of the apparatus increases as compared with the case using a lens.